The outcome of the trial hardly matters: The defendant, a former hip-hop manager for artists like the Game and Gucci Mane, has already been sentenced to life in prison for running a multimillion-dollar cocaine ring.

But the federal murder-for-hire trial of James Rosemond — known in rap circles as Jimmy Henchman — has provided a rare glimpse into a New York hip-hop feud that lasted for more than four years and ended with the fatal shooting of an associate of the rapper Curtis Jackson, better known as 50 Cent. Closing arguments are expected on Monday in Federal District Court in Manhattan.

Four former members of Mr. Rosemond’s drug gang have taken the stand over the last three weeks to describe the long-running conflict between their boss and G-Unit, the rap group founded by 50 Cent and Tony Yayo and managed by Chris Lighty.

The feud started in early 2005 when the Game put out a debut solo album, and 50 Cent expelled him from G-Unit during a live radio show on Hot 97. The Game went to the station with a big entourage to confront 50 Cent. Shots were fired. One man was wounded.

It escalated in March 2007, when Tony Yayo and a member of the G-Unit entourage, Lowell Fletcher, assaulted Mr. Rosemond’s 14-year-old son on West 25th Street. Mr. Fletcher, a Bloods gang member whose street name was Lodi Mack, went to prison for the assault and drug possession; Tony Yayo, whose given name is Marvin Bernard, received 10 days of community service.

Not satisfied, Mr. Rosemond, 49, pursued revenge against G-Unit for the next two years, shooting up the homes and torching the cars of his enemies, his former associates testified. Finally, on Sept. 27, 2009, prosecutors say, Mr. Rosemond orchestrated the shooting of Mr. Fletcher on Jerome Avenue in the Bronx, just two weeks after he left prison.

Witnesses said a dispute that began as the usual posturing between hip-hop personas, calculated to excite fans and sell albums as both 50 Cent and the Game released insulting raps about each other, became for Mr. Rosemond a personal vendetta toward anyone connected with G-Unit.

“He said, ‘These dudes ain’t going to be happy until they go to a funeral,’ ” testified Khalil Abdullah, who said he was one of Mr. Rosemond’s managers in the drug ring.

Mr. Abdullah also testified last year, when Mr. Rosemond was convicted in Federal District Court in Brooklyn of running a cocaine ring that pulled in $11 million a year. Prosecutors in Manhattan sought a separate trial on the murder charge for Mr. Rosemond and one of his alleged co-conspirators, Rodney Johnson.

Mr. Rosemond’s lawyer, Bruce J. Maffeo, has hammered away at the credibility of the prosecution’s witnesses, who testified on promises of reduced sentences for murder and drug convictions.

In his cross-examinations, Mr. Maffeo also has stressed that Mr. Rosemond was in Miami at the time of the murder and that he never explicitly told his associates he wanted Mr. Fletcher to die.

Mohammed Stewart, 36, told the jury he was one of Mr. Rosemond’s top henchmen until his arrest in April 2010, going by the nickname “Tef.”

Mr. Stewart, who has a long history as a petty drug dealer, described shooting up the entrance of Mr. Lighty’s company, Violator Records, in 2005 in retaliation for the gunfight outside of Hot 97.

As the feud escalated, Mr. Stewart said he was asked by Mr. Rosemond to take part in several tit-for-tat acts of violence. In 2007, he slashed Mr. Lighty’s brother with a razor in the street. He also admitted he had shot up a house on Staten Island belonging to Baja Walters, a road manager for G-Unit.

Mr. Stewart said he spent many nights with Mr. Rosemond staking out 50 Cent, Tony Yayo or Mr. Lighty, looking for a chance to shoot them.

“He said that, you know, they’re not going to understand what it is until they are carrying a coffin and they’re crying, like ‘I miss my homie,’ ” Mr. Stewart said.

Mr. Abdullah said the tensions between Mr. Rosemond and G-Unit began to heat up in December 2006 during the Mixtape Awards at the Apollo Theater. That night, Tony Yayo accosted Mr. Rosemond and started yelling at him about the Game’s insults.

A member of Tony Yayo’s entourage flashed a gun, and Mr. Rosemond’s group left out a back exit, Mr. Abdullah said. Later that night, Mr. Abdullah said he hired two people to pump several bullets into Tony Yayo’s Bentley as it idled on Madison Avenue in Harlem.

A few days later, Mr. Abdullah said Mr. Rosemond had told him that the rapper Sean Combs, now known as Diddy, tried to broker a truce in his office between Mr. Rosemond and Mr. Lighty. But the two managers started scuffling, and Mr. Combs had to break up the fight.

Brian McCleod, a low-level drug dealer who did errands at Mr. Rosemond’s studio in the early 2000s, described how he lured Mr. Fletcher to Jerome and Mount Eden Avenues in the Bronx by promising to give him money and to introduce him to women.

Mr. McCleod, whose nickname is Slim, said he had gone to prison in 2004 after the police caught him as he carried nine kilograms of cocaine out of a stash house for Mr. Rosemond. While incarcerated, he said, he befriended a Bloods gang member who was close to Mr. Fletcher.

A day after Mr. McCleod was released in August 2009, he met with Mr. Rosemond outside Central Park. “I told him I had a line on the individual who slapped his son,” Mr. McCleod testified.

A few days later, Mr. McCleod said the pair met at the food court in the Whole Foods at Columbus Circle, where Mr. Rosemond offered him $30,000 to lead Mr. Fletcher into an ambush.

At first, Mr. McCleod said, Mr. Rosemond wanted to shoot Mr. Fletcher himself, saying “it’s going to be so fast and so quick no one will know.” But Mr. McCleod persuaded him to hire a mutual friend, Derrick Grant, to pull the trigger. They received a kilo of cocaine as payment.

Mr. Abdullah testified that Mr. Rosemond admitted to hiring the men who shot Mr. Fletcher. They were standing outside Mobay Restaurant in Harlem a few days after the murder when Mr. Rosemond started telling the story. “He said Slim’s man came out of nowhere and clapped the dude up,” Mr. Abdullah said.

Mr. Abdullah said he asked Mr. Rosemond if the murder could be traced back to him. “He said, ‘Nah, dude is a gangbanger,’ ” Mr. Abdullah recalled. “ ‘That [expletive] happen in the Bronx.’ ”

A version of this article appears in print on , on Page A18 of the New York edition with the headline: At Hip-Hop Manager’s Murder Trial, Witnesses Recount Long-Running Feud. Order Reprints | Today’s Paper | Subscribe